CN113696103B - Long-service-life steel rail treatment method - Google Patents
Long-service-life steel rail treatment method Download PDFInfo
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- CN113696103B CN113696103B CN202110947223.9A CN202110947223A CN113696103B CN 113696103 B CN113696103 B CN 113696103B CN 202110947223 A CN202110947223 A CN 202110947223A CN 113696103 B CN113696103 B CN 113696103B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
- C23C22/08—Orthophosphates
- C23C22/22—Orthophosphates containing alkaline earth metal cations
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Abstract
The application belongs to the technical field of metal material processing, and particularly relates to a long-service-life steel rail treatment method. The method comprises the following steps: acquiring residual stress values of the first end part, the middle part and the second end part; respectively carrying out shot blasting on the first end part, the middle part and the second end part according to the residual stress value so as to reduce the difference between any two of the first end part, the middle part and the second end part, and obtaining a shot-blasted steel rail; carrying out surface protection treatment on the shot blasting steel rail to obtain a steel rail with a protective layer; the consistent surface residual stress can effectively reduce the fatigue crack propagation, delay the generation of fatigue failure and simultaneously improve the resistance of the material to corrosion; the steel rail with the protective layer can protect the steel rail against corrosion caused by atmosphere and accumulated water in the using process, and the steel rail and the protective layer have a certain protective effect and a certain action of superposition, so that the service life is prolonged.
Description
Technical Field
The application belongs to the technical field of metal material processing, and particularly relates to a long-service-life steel rail treatment method.
Background
The production process of the steel rail mainly comprises the working procedures of heating, cooling, straightening and the like. In the heating and cooling processes, the steel rail is subjected to the action of rolling force, solid phase transformation force and shrinkage thermal stress to generate uneven plastic deformation at each part, so that certain residual stress is generated. In addition, in the final straightening process, the steel rail is subjected to elastic-plastic bending deformation for multiple times under the action of straightening force, so that the residual stress in the steel rail is redistributed, and straightening residual stress is generated. Thus, the rail production residual stress is the result of the superposition of hot rolling-cooling residual stress and straightening residual stress.
In the running process of the locomotive, the proportion of compressive stress of the steel rail in the length direction is large, large tensile load is borne at the waist of the steel rail, locomotive alternating stress and steel rail residual stress are superposed at the position, the stress at the moment can reach or even exceed the fatigue limit of the material, and the steel rail is easy to crack, so that the service safety is influenced. The residual stress generated by the circular rolling contact of the steel rail and the production residual stress are mutually superposed, and the final residual stress state of the steel rail is determined. The distribution state of the residual stress has important influence on the initiation, the fracture mode and the fracture position of the fatigue crack of the serving steel rail.
Atmospheric corrosion is another major cause of rail failure. Factors such as humid air, rainwater, polluted gas, day and night temperature difference and the like in the atmosphere provide conditions for electrochemical corrosion of the steel rail. Particularly, the environment in the railway tunnel is that the air humidity in the tunnel is high, and the local part is immersed in water. From the field observation condition, tunnel water leakage conditions exist in steel rail corrosion sections, and the ballast bed is wet; running water exists beside some roads, and the running water can bring water to the rail web or the rail bottom when a train passes through at a high speed; the constant leakage of groundwater also causes the air in the tunnel to become very humid. Due to the fact that the humidity in the tunnel is high, and the temperature of different environments acts, the steel rail contains various chemical components such as iron and carbon, and the electrode potentials of the components are different, and an electrochemical corrosion reaction is generated on the surface of the steel rail.
By rail use survey: in a tunnel with accumulated water or a road section with flowing water in ditches at two sides of a track, the corrosion condition at the outer side of a steel rail is serious, a large-area one-layer or multi-layer lamellar corrosion product appears on the upper surface of the rail bottom of the outer rail web, a cavity is formed between the corrosion product and a base body and is easy to peel off from the base body, and the corrosion is caused by stress corrosion cracking,
therefore, how to solve the problem of crack initiation and propagation of the rust products on the surface of the steel rail during the service period of the steel rail needs to be focused and solved.
Disclosure of Invention
The application provides a long-service-life steel rail treatment method, which aims to solve the technical problem of service steel rail cracking.
In a first aspect, the present application provides a long service life steel rail treatment method, comprising the following steps:
acquiring residual stress values of the first end part, the middle part and the second end part;
respectively carrying out shot blasting on the first end part, the middle part and the second end part according to the residual stress value so as to reduce the difference between any two of the first end part, the middle part and the second end part, and obtaining a shot-blasted steel rail;
carrying out surface protection treatment on the shot blasting steel rail to obtain a steel rail with a protective layer;
wherein the conditions of the shot peening include: the moving speed is 1.5-6 m/min, and the air pressure is 0.5-0.9 MPa. Optionally, if the residual stress value is 100-150 MPa, performing shot blasting at a moving speed of 2.5-6 m/min under the condition that the air pressure is 0.5-0.8 MPa;
if the residual stress value is 150-220 MP, carrying out shot blasting treatment at a moving speed of 1.5-5 m/min under the condition that the air pressure is 0.7-0.9 MPa;
if the residual stress value is-130 to-90 MP, carrying out shot blasting treatment at the moving speed of 1.5 to 6m/min under the condition that the air pressure is 0.5 to 0.8 MPa; the stress testing direction is the length direction of the steel rail, the positive value is tensile stress, and the negative value is compressive stress.
Optionally, the stress of the shot-blasted steel rail is-20 to 20MPa, wherein the stress testing direction is the length direction of the steel rail, a positive value is tensile stress, and a negative value is compressive stress.
Optionally, the shot blasting treatment is performed by using at least one of alloy shots and alloy sand, the grain diameters of the alloy shots and the alloy sand are 0.6-1.2 mm respectively, and the spraying amount is 100-200 Kg/min.
Optionally, the mass ratio of the alloy sand to the alloy shot is 1:3-1: 1.
optionally, the surface roughness of the peened steel rail includes: ra > 6 μm, rz > 50 μm, rpc > 40.
Optionally, the shot peening further comprises a pre-surface cleaning treatment and a post-shot peening sweeping.
Optionally, the surface protection treatment comprises chemical treatment, wherein the chemical treatment comprises immersing in an oxidation treatment solution, and keeping the temperature at 45-60 ℃ for 1-2h.
Optionally, the oxidation treatment liquid comprises the following components in concentration by mass: 10-15 g/L phosphoric acid, 70-100 g/L nitrate, 10-30 g/L manganese oxide, 40-50 g/L ferric manganese phosphate, 1-3g/L surfactant and 2-10g/L corrosion inhibitor.
Optionally, the surface protection treatment further comprises a painting treatment.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
according to the method provided by the embodiment of the application, the residual stress values of the first end part, the middle part and the second end part are obtained, and the moving speed and the air pressure of shot blasting treatment are correspondingly adjusted for different types and sizes of the residual stress at different parts; aiming at the types and the sizes of residual stress of different parts of the steel rail, the moving speed and the air pressure can be the same or different, and the final effect of shot blasting treatment is that the stress sizes and the directions on the surface of the shot blasting steel rail tend to be consistent; the consistent surface residual stress can effectively reduce the fatigue crack propagation, delay the generation of fatigue failure and simultaneously improve the corrosion resistance of the steel rail. The steel rail with the protective layer is obtained by performing surface protection treatment on the shot-blasting steel rail, so that the steel rail has a certain protective effect on corrosion caused by electrochemical corrosion and the like due to atmosphere and accumulated water in the using process, and the steel rail is prevented from cracking caused by stress better.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without inventive labor.
Fig. 1 is a schematic flow chart of a long-service-life steel rail processing method provided in an embodiment of the present application;
FIG. 2 is a corrosion resistance test chart of examples of the present application and comparative examples;
FIG. 3 is a graph showing fatigue tests of examples of the present application and comparative examples;
FIG. 4 is a graph comparing the corrosion resistance of examples of the present application and comparative examples;
FIG. 5 shows the appearance of a coating thickness sample of the present application after salt fog scratching.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.
The embodiment of the application provides a long-service-life steel rail processing method, and as shown in fig. 1, the method comprises the following steps:
s1, obtaining residual stress values of a first end part, a middle part and a second end part;
s2, respectively carrying out shot blasting on the first end part, the middle part and the second end part according to the residual stress value so as to reduce the difference between any two of the first end part, the middle part and the second end part and obtain a shot blasting steel rail;
s3, performing surface protection treatment on the shot blasting steel rail to obtain a steel rail with a protection layer; wherein the condition of the shot peening includes: the moving speed is 1.5-6 m/min, and the air pressure is 0.5-0.9 MPa.
In the embodiment of the application, shot blasting is carried out on the surface of the steel rail, so that the residual stress on the surface of the steel rail is adjusted, uniform compressive stress is generated on the surfaces of the head, the waist and the bottom of the steel rail, and the crack initiation probability is reduced; chemical treatment is carried out to form a protective layer with uniform, compact and good adhesion thickness of about 50-100 mu m on the surface of the steel rail, so that the effect of delaying corrosion is achieved; the steel rail with long service life is obtained by adjusting the residual stress and the oxide layer on the surface of the steel rail.
In general, the production residual stress (longitudinal residual stress) of a steel rail is distributed in a C shape, that is, the rail head and the rail bottom are in a tensile stress state, and the rail web is in a compressive stress state. The residual stress of the surface layer of the steel rail has important influence on the fatigue strength and the corrosion resistance of the steel rail, the surface micro-cracks can be continuously enlarged by the residual tensile stress of the surface layer, the generation and the expansion of the cracks are accelerated, the fatigue crack expansion can be effectively relieved by the residual compressive stress of the surface layer, the generation of fatigue failure is delayed, and meanwhile, the resistance of the material to corrosion is improved.
In the embodiment of the application, the shot blasting treatment can also be sand blasting treatment, and the rail shot blasting/sand blasting is carried out in a totally closed space
In the embodiment of the application, through actual measurement, the residual stress of the rail web is compressive stress, and the residual stress of the rail head and the rail bottom is tensile stress along the length direction of the steel rail, the magnitude of the residual stress is generally 100-200MPa (normal temperature), and can reach 300MPa when the magnitude is larger. Through the existing residual stress, the moving speed and the air pressure of the surface shot blasting treatment are adjusted and adjusted to obtain uniform pressure stress, and the crack initiation probability is reduced.
As an alternative embodiment, the stress of the shot-blasted steel rail can be-20 to 20MPa, the stress test direction is the length direction of the steel rail, the positive value is tensile stress, and the negative value is compressive stress.
In the embodiment of the application, the stress after shot blasting is small, and cracks generated by the stress can be reduced.
As an alternative embodiment, if the residual stress value is 100-150 MPa, the shot blasting is carried out at a moving speed of 2.5-6 m/min under the condition that the air pressure is 0.5-0.8 MPa;
if the residual stress value is 150-220 MP, carrying out shot blasting treatment at a moving speed of 1.5-5 m/min under the condition that the air pressure is 0.7-0.9 MPa.
If the residual stress value is-130 to-90 MP, carrying out shot blasting treatment at the moving speed of 1.5 to 6m/min under the condition that the air pressure is 0.5 to 0.8 MPa; wherein, the stress testing direction is the length direction of the steel rail, the positive value is tensile stress, and the negative value is compressive stress.
As an alternative embodiment, the shot peening further comprises a pre-surface cleaning process and a post-shot sweeping.
In the embodiment of the application, the surface cleaning treatment is carried out before the steel rail shot blasting. The oil stain, dust or other foreign matters on the surface of the steel rail need to be cleaned. The surface of the steel rail is inspected, and the contour is complete without defects such as cracks, indentation, abnormal abrasion and the like. Removing the oxide layer of the steel rail, eliminating the surface stress of the material, reducing the risk of stress corrosion cracking, and coating a complete, compact and corrosion-resistant protective layer with good adhesive force; the surface of the shot blasting steel rail is always stained with sand grains or dust and can be cleaned by adopting compressed air. The rails remain dry and are placed in dry and clean places and should be post-treated as soon as possible.
As an optional embodiment, at least one of the alloy shot and the alloy sand is adopted in the shot blasting treatment, the grain diameter of the alloy shot and the grain diameter of the alloy sand are respectively 0.6-1.2 mm, and the spraying amount is 100-200 Kg/min.
In the embodiment of the application, the air compressor can be of a type of 40kw and a maximum pressure of 0.9MPa, wherein an oil-water separator can be installed, and the water content and the oil content in the compressed air are controlled within an allowable range according to the ASTM 4285 standard; the air pressure is ensured to be within the range of 0.5-0.9 MPa, the shot blasting nozzle can be made of tungsten carbide or boron carbide materials, the aperture can be 6-10 mm, the injection quantity of shot blasting is about 100-200 Kg/min, the distance between the shot blasting and a steel rail can be 100-800 mm, the shot blasting distance can be 100-800 mm during manual shot blasting, and the moving speed of the shot blasting nozzle can be 1.5-6 m/min.
In the embodiment of the application, the shot blasting comprises at least one of steel grit and steel shot, stainless steel shots or steel grit of different types are selected, 304 stainless steel shots can be selected as the steel shots, the grain diameter of the steel shots is 0.3mm, 0.6mm, 0.8mm and 1.2mm, and GH-18 can be selected as the steel grit type.
As an optional implementation mode, the mass ratio of the alloy sand to the alloy shot is 1:3-1: 1. The steel shot can effectively remove the iron scale on the surface of the steel rail by using the steel shot, meanwhile, the steel shot has larger mass than steel grit, larger impact force on the surface of the steel rail and obvious effect on eliminating the stress concentration on the surface of the material, the edges and corners of the steel grit are beneficial to surface roughness processing, certain roughness is beneficial to post-processing quality, but the steel grit is easy to break and is consumed faster than the steel shot.
In the embodiment of the present application, the arithmetic mean deviation of the profile is represented by Ra: the arithmetic mean of the absolute values of the profile offsets over the sample length (lr). In actual measurement, the larger the number of measurement points, the more accurate Ra. The maximum height of the profile is expressed by Rz: the distance between the peak and valley lines of the profile. Roughness peak counts are expressed in Rpc.
In the embodiment of the application, the primer can be super-strong epoxy paint 45751 or epoxy zinc-rich paint 15360; the finish paint can be a polysiloxane paint 55000 or an acrylic polyurethane paint 55210. The primer and the finish are commercial coatings sold in the market, the rainbow old brand coating is recommended, the specific construction process refers to a coating use instruction, the steel rail spraying treatment is carried out in a drying room capable of accommodating a steel rail with the length of 12.5 meters, high-performance airless spraying equipment is adopted, after the first coating is completed, the steel rail is baked according to the instruction and placed for 8-30 hours, then the second coating is carried out, each coating film is uniformly and flatly sprayed, the defects of flowing, pinholes, fish eyes, missing coating, bubbles and the like are avoided, the construction process needs to be ventilated enough, open fire is forbidden, and safety is ensured.
As an alternative embodiment, the surface protection treatment comprises a chemical treatment, wherein the chemical treatment comprises immersing in an oxidation treatment solution and keeping the temperature at 45-60 ℃ for 1-2h.
In the examples of the present application, the steel rail surface is formed with Fe by chemical treatment 3 O 4 The oxide film as the main component makes the treated rail have good corrosion resistance. The processed film is a dark black or red black film and has good compact protective performance.
In the embodiment of the application, the shot rail is immersed in an oxidation treatment tank, the oxidation treatment tank is filled with oxidation treatment liquid, the oxidation treatment liquid flows in a circulating mode through a circulating pump, a filter is arranged to filter impurities in the oxidation treatment liquid to ensure the concentration of the oxidation treatment liquid, and a heater is arranged to heat the oxidation treatment liquid to ensure that the shot rail reacts in the oxidation treatment liquid at a preset temperature to form an oxidation film.
As an optional implementation mode, the mass ratio of the alloy sand to the alloy shot is 1:3-1: 1.
As an alternative embodiment, the surface roughness of the peened steel rail includes: ra > 6 μm, rz > 50 μm, rpc > 40.
As an alternative embodiment, the surface protection treatment comprises a chemical treatment, and the chemical treatment comprises immersing in an oxidation treatment solution and keeping the temperature at 45-60 ℃ for 1-2h.
As an alternative embodiment, the components of the oxidation treatment liquid include, in mass concentration: 10-15 g/L phosphoric acid, 70-100 g/L nitrate, 10-30 g/L manganese oxide, 40-50 g/L ferric manganese phosphate, 1-3g/L surfactant and 2-10g/L corrosion inhibitor.
In the embodiment of the present application, the oxidation treatment liquid includes, by mass concentration: 7-17 g/L nitric acid, 70-100 g/L barium nitrate or 80-100 g/L calcium nitrate, 16-30 g/L manganese dioxide or 10-15 g/L manganese trioxide or 40-50 g/L ferric manganese phosphate salt or 5-15 g/L manganese dihydrogen phosphate, 1-3g/L surfactant and 2-10g/L corrosion inhibitor. The oxides of manganese can be replaced by 1 to 5g/L of sodium chlorate.
In the embodiment of the present application, the oxidation treatment liquid includes, by mass concentration: 10-15 g/L phosphoric acid or 7-17 g/L nitric acid, 70-100 g/L barium nitrate or 80-100 g/L calcium nitrate, 16-30 g/L manganese dioxide or 10-15 g/L manganese trioxide or 1-5 g/L sodium chlorate, 40-50 g/L ferromanganese phosphate or 5-15 g/L manganese dihydrogen phosphate, 1-3g/L surfactant and 2-10g/L corrosion inhibitor.
In the embodiment of the application, compared with an alkaline treatment agent, the oxidation treatment liquid has the advantages of low heating temperature, low energy consumption, compact oxide layer, good adhesiveness and good effect on improving the corrosion resistance of the steel rail. In the embodiment of the application, the surfactant can comprise at least one of nonylphenol polyoxyethylene ether, octadecylamine polyoxyethylene ether or coconut oil fatty acid diethanolamide.
As an alternative embodiment, the surface protection treatment further comprises a painting treatment.
In the embodiment of the application, the corrosion inhibitor can comprise at least one of hexamethylenetetramine, quinihibitor 8901 or Nichira chemical IBIT NH-D corrosion inhibitor. As an alternative embodiment, the surface protection treatment further comprises a painting treatment.
In the examples of the present application, the painting process comprises coating the surface with a primer of 80-180 μm and a top coat of 100-280 μm, or chemically treating the surface of the rail to form an oxide layer to protect the rail from corrosion.
Example 1
Take U71Mn, 60Kg/m rail as an example. According to the technical scheme of the application, the sample is processed, the surface of the sample is made of stainless steel shots with the grain size of 0.8mm and GH-18 steel grit, the mass ratio of the stainless steel shots to the GH-18 steel grits is 1.5:1, the compressed air parameter is 0.8MPa, the surface roughness Ra is 8.4 mu m after treatment, rz is 58.5 mu m, rpc 64, the pressure stress of the detected rail waist is minus 10MPa, the tensile stress of the rail head is 8MPa, and the tensile stress of the rail bottom is 11MPa. Coating the steel rail, wherein the primer is ultra-strong epoxy paint 45751 with the average thickness of 140 mu m, and the finish paint is polysiloxane paint 55000 with the average thickness of 210 mu mRespectively carrying out a neutral salt spray accelerated corrosion constant load pull-pull fatigue test for 400 hours on the treated samples, wherein the surface of the steel rail sample is not corroded after the neutral salt spray fatigue test, the maximum stress value of the fatigue test is 500MPa, the minimum stress value is 200MPa, and the cycle number is 10 5 Secondly, the loading frequency is 1000 times/min, the test sample is not broken after the test, and the surface has no crack.
Example 2
U75V and 60Kg/m steel rail are taken as examples. According to the technical scheme of the application, the sample is processed, the surface treatment adopts stainless steel shots and GH-18 steel grits with the grain size of 0.8mm, the compressed air parameter with the mass ratio of 1:1 of the stainless steel shots and the GH-18 steel grits adopts 0.9MPa pressure, the surface roughness Ra 10.1 mu m, the Rz 83.6 mu m and the Rpc 68 are obtained after the treatment, the stress of the detected rail waist is minus 16MPa, the tensile stress of the rail head is 13MPa, and the tensile stress of the rail bottom is 17MPa. Coating the steel rail, wherein the primer is made of super-strong epoxy paint 45751 with the average thickness of 180 mu m, the finish is made of polysiloxane paint 55000 with the average thickness of 230 mu m, the treated samples are subjected to a neutral salt spray accelerated corrosion constant load pull-pull fatigue test for 400 hours respectively, the surface of the steel rail sample is not rusted after the neutral salt spray fatigue test, the maximum stress value of the fatigue test is 500MPa, the minimum stress value is 200MPa, and the cycle number is 10 5 And secondly, loading frequency is 1000 times/minute, the test sample is not broken after the test, and the surface has no crack.
Example 3
Take U68Cu, 60Kg/m rail as an example. According to the technical scheme of the application, the sample is processed, and stainless steel shots and GH-18 steel grits with the grain size of 0.8mm are adopted for surface treatment, and the mass ratio of the stainless steel shots to the GH-18 steel grits is 1.5:1, the compressed air parameters adopt 1.0MPa pressure, the surface roughness Ra is 8.5 mu m, the Rz is 93.0 mu m and the Rpc is 51, the pressure stress of the rail web is detected to be minus 3MPa, the tensile stress of the rail head is 0MPa, and the tensile stress of the rail bottom is 6MPa. When the steel rail is chemically treated, the treatment fluid adopts a formula of 12g/L phosphoric acid, 7g/L nitric acid, 3g/L sodium chlorate, 8g/L manganese dihydrogen phosphate, 1g/L surfactant and 2-10g/L corrosion inhibitor, the steel rail is soaked for 2 hours at 55 ℃, the treated samples are subjected to 240-hour neutral salt spray accelerated corrosion and constant load pull-pull fatigue tests respectively, the corrosion proportion of the surface of the steel rail sample after the neutral salt spray fatigue test is about 20 percent, and the fatigue test has the maximum stressThe force value is 500MPa, the minimum stress value is 200MPa, and the cycle number is 10 5 Secondly, the loading frequency is 1000 times/min, the test sample is not broken after the test, and the surface has no crack.
Comparative example 1
And (3) corrosion resistance test: a U75V and 60Kg/m steel rail is selected and used for cutting two sections of unprocessed steel rail samples, wherein one section is directly subjected to a 240h salt spray test, the appearance of the test sample is shown in the left picture of a figure 2, and the other section is treated according to the method described in example 1, and the appearance of the obtained steel rail sample after being subjected to 400h salt spray accelerated corrosion is shown in the right picture of the figure 2.
And (3) fatigue testing: a sample of untreated rail was taken and processed into a fatigue mechanical test specimen, a comparison was made of mechanical fatigue specimens which were likewise obtained on rails and which were further subjected to the shot peening and painting treatments described in example 1, the following test conditions being used for both fatigue specimens: the maximum stress value was 450MPa, the minimum stress value was 250MPa, and the loading frequency was 1000 times/min, so that the untreated test specimen broke after week 53000, as shown in the left panel of FIG. 3, and the treated test specimen 5X 10 5 No breakage occurred after the week, as shown in the right panel of FIG. 3.
Comparative example 2
The steel rail is processed by selecting U75V and 60Kg/m steel rail, performing conventional shot blasting and oxidation treatment in the prior art, wherein the steel rail is as the left drawing in figure 4, and the steel rail is processed by the treatment mode of example 2, wherein the steel rail is as the right drawing in figure 4, and both are subjected to sand blasting treatment and coating treatment. The steel rail has the characteristics of low surface stress and high corrosion resistance, the left graph takes the insulated coated steel rail as a design starting point, and the right graph mainly takes the service life of the steel rail as a starting point for inventing and creating, so that the insulating property requirement of the coating is high, the coating and processing cost is high, and the performance of the coating of the steel rail cannot reach the level of the coating, but the corrosion resistance of the steel rail is improved on the premise of low overall processing cost, and the service life is prolonged.
Comparative example 4
This work has developed the optimization test on the steel shot steel grit ratio, the range selection of air pressure, and wherein the change includes:
(1) In the comparative example 1, stainless steel shots with the grain diameter of 0.8mm and GH-18 steel grits are adopted, the proportion of the steel shots and the steel grits is changed, the mass ratio of the stainless steel shots and the steel grits is 1: 2, the compressed air parameter adopts 0.9MPa pressure, the surface roughness Ra is 13.7 mu m after treatment, the detected rail web has the stress of-19 MPa, the rail head has the tensile stress of 23MPa, the rail bottom has the tensile stress of 32MPa, and the residual stress does not reach the expected range of-20 MPa.
(2) In comparative example 1, stainless steel shot with a particle size of 0.8mm and GH-18 steel grit are used in a mass ratio of 1:1, a pressure of 0.7MPa is adopted by changing compressed air parameters, the surface roughness Ra 9.5 μm after treatment is achieved, the rail waist is detected to have a stress of-21 MPa, the rail head is detected to have a tensile stress of 17MPa, the rail bottom is detected to have a tensile stress of 24MPa, and the residual stress does not reach the expected range of-20 MPa.
Comparative example 5
This work performed optimization experiments on coating thickness range selection, where changes included:
in comparative example 2, stainless steel shot with a grain size of 0.8mm and GH-18 steel grit are used for surface treatment, the compressed air parameter with a mass ratio of 1:1 is 0.9MPa, the surface roughness Ra is 10.1 μm after treatment, rz is 83.6 μm, rpc 68, the stress of the rail waist is detected to be-16 MPa, the tensile stress of the rail head is detected to be 13MPa, and the tensile stress of the rail bottom is detected to be 17MPa. The steel rail is coated, the thickness of the coating is reduced, the primer adopts super-strong epoxy paint 45751 and has the average thickness of 120 mu m, the finish paint adopts polysiloxane paint 55000 and has the average thickness of 160 mu m, the neutral cross salt spray accelerated corrosion of the treated sample is respectively carried out for 400 hours, and the cross-section expansion width of the sample after the coating is reduced is larger than that before the coating is reduced. Referring to FIG. 5, the left is the appearance of the coating thickness sample of example 1 after being crossed by salt fog, and the right is the appearance of the coating thickness sample after being thinned after being crossed by salt fog.
Comparative example 6
20 standard mechanical samples are taken from the steel rail, and after the steel rail is processed by using the processing mode, periodic fatigue test and neutral salt spray accelerated corrosion are carried out, wherein the periodic fatigue test comprises the following steps: the loading stress is 200-500Mpa, the loading frequency is 1000 times/minute, 10 ten thousand cycles of tests show that as shown in table 1, 2 mechanical samples of 20 mechanical samples have fatigue fracture when 10 ten thousand cycles are not reached, the mechanical samples which are not treated in the comparative example 1 are subjected to the same mechanical test, 15 mechanical samples of 20 mechanical samples have fracture when 10 ten thousand cycles are not reached, the mechanical samples in the comparative example 2 are subjected to the same mechanical test, 6 mechanical samples of 20 mechanical samples have fracture when 10 ten thousand cycles are not reached, meanwhile, the stresses of the rail head, the rail web and the rail bottom of the steel rail treated in the embodiment are obviously smaller than those of the mechanical samples in the comparative example 4, and the stress types and the stress sizes tend to be more consistent.
Table 1.
Table 2.
The neutral salt spray accelerated corrosion comprises 400-hour neutral salt spray accelerated corrosion, and the corrosion rate of the surface of the steel rail is detected.
As shown in table 2 and fig. 2, the surface of the steel rail treated in the example is not rusted after the neutral salt spray accelerated corrosion for 400 hours, the surface of the steel rail treated in the example 2 is not rusted after the neutral salt spray accelerated corrosion for 400 hours, and 100% of the surface of the steel rail untreated in the comparative example 1 is rusted after the neutral salt spray accelerated corrosion for 400 hours. As shown in Table 1, the fracture probability of the untreated steel rail in the comparative example 1 is more than 70%, the fracture probability of the steel rail in the example treated by the method is less than 15%, and the fracture sample (matched with the table) is shown in FIG. 3.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (3)
1. A long service life steel rail treatment method is characterized by comprising the following steps:
acquiring residual stress values of the first end part, the middle part and the second end part;
and respectively carrying out shot blasting on the first end part, the middle part and the second end part according to the residual stress value so as to reduce the difference between any two of the first end part, the middle part and the second end part to obtain a shot blasting steel rail, wherein the mass ratio of alloy sand and alloy shots adopted in the shot blasting treatment is 1:3-1:1, the stress of the shot blasting steel rail is-20 MPa, and the surface roughness of the shot blasting steel rail comprises the following steps: ra is more than 6 mu m, rz is more than 50 mu m, and Rpc is more than 40;
carrying out surface protection treatment on the shot blasting steel rail to obtain a steel rail with a protective layer;
wherein the conditions of the shot peening include: the moving speed is 1.5-6 m/min, and the air pressure is 0.5-0.9 MPa;
the surface protection treatment comprises chemical treatment and paint spraying treatment, wherein the chemical treatment comprises immersing in an oxidation treatment liquid and keeping the temperature at 45-60 ℃ for 1-2h, the paint spraying treatment comprises covering the surface with a primer of 80-180 mu m and a finish paint of 100-280 mu m, and the oxidation treatment liquid comprises the following components in percentage by mass: 10-15 g/L of phosphoric acid, 70-100 g/L of nitrate, 10-30 g/L of manganese oxide, 40-50 g/L of ferromanganese phosphate, 1-3g/L of surfactant and 2-10g/L of corrosion inhibitor, wherein the surfactant comprises at least one of nonylphenol polyoxyethylene ether, octadecylamine polyoxyethylene ether or coconut oil fatty acid diethanolamide;
if the residual stress value is 100-150 MPa, carrying out shot blasting treatment at the moving speed of 2.5-6 m/min under the condition that the air pressure is 0.5-0.8 MPa;
if the residual stress value is 150-220 MP, carrying out shot blasting treatment at a moving speed of 1.5-5 m/min under the condition that the air pressure is 0.7-0.9 MPa;
if the residual stress value is-130 to-90 MP, carrying out shot blasting treatment at the moving speed of 1.5 to 6m/min under the condition that the air pressure is 0.5 to 0.8 MPa; wherein, the stress testing direction is the length direction of the steel rail, the positive value is tensile stress, and the negative value is compressive stress.
2. The method according to claim 1, wherein the shot blasting is performed at a shot size of 100 to 200Kg/min.
3. The method of claim 1, wherein the shot peening further comprises a pre-surface cleaning process and a post-shot sweep.
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| CN1884616A (en) * | 2006-06-23 | 2006-12-27 | 攀枝花钢铁(集团)公司 | Corrosion-resistant railway rail and production method thereof |
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| CN106048144A (en) * | 2016-07-27 | 2016-10-26 | 东南大学 | Method for regulating and controlling laser shock shot-blasting stress of laser additive thin-walled part |
| CN111013987A (en) * | 2019-12-12 | 2020-04-17 | 广东中烨建筑钢构有限公司 | Steel structure anticorrosion construction process |
| CN111621629B (en) * | 2020-06-29 | 2022-03-18 | 安徽天航机电有限公司 | Shot blasting process for nut surface strengthening |
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